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Ajw final /certified fixed orthodontic courses by Indian dental academy
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Ajw final /certified fixed orthodontic courses by Indian dental academy

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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078

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Ajw final /certified fixed orthodontic courses by Indian dental academy Ajw final /certified fixed orthodontic courses by Indian dental academy Presentation Transcript

  • DEPARTMENT OF ORTHODONTICS www.indiandentalacademy.com INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com
  • Dr NIPUN T JOHN II nd M D Swww.indiandentalacademy.com
  • History of Orthodontic Wires • Until 1930-orthodontic wires were made of GOLD • 1930-advent of stainless steel & refinement in drawing process to form wires with improved properties, GOLD lost its ground. Stainless steel was perfected for the orthodontic use by Bresrley and Sheffield of U.S • By 1950- almost 300 different series of S/S alloys were used in the field of orthodontics. • Chromium 17-25% • Nickel 8-25% with a balance being iron www.indiandentalacademy.com
  • Introduction • An ideal archwire is one which move teeth with a light continuous force. • These forces should not decay rapidly because material loses its elasticity, as a small amount of tooth movement causes a large change in the force levels. Hence mechanotherapy depends on elastic behavior of the material and biochemical reaction of the teeth. www.indiandentalacademy.com
  • Properties of ideal archwire STRENGTH SPRINGY RESELIENT WELDABLE ESTHETIC POOR BIOHOST GOOD RANGE SPRING BACK LOW FRICTION FORMABLE TOUGH BIOCOMPATABILE www.indiandentalacademy.com
  • Manufacturing of stainless steel orthodontic wires • These alloys are usually standardized and formulated based on AISI specifications. MELTING INGOT FORMATION ROLLING DRAWING www.indiandentalacademy.com
  • The selection and melting of the components of alloys influence the physical properties of wire MELTING type Composition (as per AISI) Cr Ni C Mn Si P S 302 17-19% 8- 10 0.15 2 1 0.045 0.03 304 18-20% 8- 12 0.08 2 1 0.045 0.03 416 12-14% - 0.15 1.25 1 0.06 0.15 www.indiandentalacademy.com
  • • Pouring of the molten metal in to the mold • A non uniform chunk of metal is produced • Ingot- Granular structure, consist of crystals of component metals called as GRAINS. • The mechanical properties of the ingot is controlled by its granular structure. • When the ingot is cooled, grains forms at once. • These growing crystals are surrounded each another. • INGOT – colony of irregularly shaped grains of different materials. INGOT FORMATION www.indiandentalacademy.com
  • • The rate of cooling and size of ingot decide the size and distribution of the grains. • The pouring and cooling process affect porosity. • Porosity can be due to – Gases dissolved in molten mass. – Byproduct of molten mass – When ingot cools the inner mass hardens later, inside the outside hardened shell, which results in additional vacuum voids. www.indiandentalacademy.com
  •  First mechanical step in process.  Ingot is rolled in series of rollers to reduce its diameter.  The individual grains retain their identity through rolling process, unless some heat treatments are carried out. Now the wire is actually an “distorted ingot”.  The squeezing and rolling of ingot alters the shape and arrangement of the crystals. ROLLING www.indiandentalacademy.com
  • • Rolling will cause the elongation of crystals into an finger like process, closely meshed with each other. • Hardness/ brittleness increases as the grain positions and arrangements are altered. • The metal is annealed by heating into high temperature, which relives the internal stress formed by rolling. • On cooling ,it resembles an original casting. • The grain size depends on the time and temperature of annealing and the rate of cooling. www.indiandentalacademy.com
  • • Ingot is reduced in to final size. • The wire is pulled through a small hole in a die. • To relive work hardening, the wire is drawn through and annealed ,several times. This will increase the strength and make the wire resistant to breakage. DRAWING www.indiandentalacademy.com
  • Cr2O3 Properties of stainless steel • When 12-30% chromium is added to steel--- -----STAINLESS STEEL. • Yield strength at room temperature- 211-1760Mpa • PASSIVATION- property of SS to resist tarnish and corrosion. Stainless steel O2 O2 O2 O2 O2 Cr Cr Cr Cr www.indiandentalacademy.com
  • CORROSION RESISTANCE OF S/S • SENSITIZATION On cold working of SS, carbide precipitates along the slip planes. As a result areas deficient in carbon will be less and carbide is uniformly distributed. they precipitate only in grain boundaries. This increases corrosion resistance • STABILIZATION Titanium ,when added 6 times to carbon, inhibits formation of chromium carbide. www.indiandentalacademy.com
  • Types of stainless steel FERRITIC AUSTENITIC ROOM TEMP 912C 1394C BCC LOW CARBON SOLUBILITY-0.02wt% FCC CARBON SOLUBILITY- 2.1wt% WHEN COOLED SLOWLY EXCESS CARBON WHICH IS NOT SOLUBLE FORMS IRON CARBIDE WHEN COOLED SUDDENLY SPONTANEOUS DIFFUSIONLESS TRANSFORMATIOM INTO BCT- HARD STRONG & BRITTLE BCTMARTENSITIC www.indiandentalacademy.com
  • • Cr-11.5-27% Ni-0% C-0.2% • AISI 400 series. • Good corrosion resistance . • Low cost. • Low strength. • Not hardenable by heat treatment. • Not readily work hardenable. • Little application in dentistry. FERRITIC-BCC www.indiandentalacademy.com
  • • Cr-11.5-17% Ni-0-2.5% C-0.15-1.2% • Can be heat treated • High strength, high hardness, Brittle. • Yield strength-492Mpa(annealed)- 1898Mpa(hardened) 230-600BHN • Less corrosion resistance. • Reduced ductility. MARTENSITIC-BCT www.indiandentalacademy.com
  • • Cr-16-26% Ni-7-22% C-0.25% • AISI 302 is basic type 18:8:0.05 • AISI 304 18:8:0.08 • AISI 316L- implants 18:8:0.03 • Commonly used by ORTHODONTIST AUSTENITIC-FCC www.indiandentalacademy.com
  • ADVANTAGES  Greater ductility and ability to undergo cold working without fracture.  Substantial strengthening during cold working.  Ease of welding  Ability to readily overcome sensitization  Less critical grain growth.  Ease of forming. www.indiandentalacademy.com
  • Stress relief in SS • It is a level of heat treatment at which the internal stresses are relived by minute slippages & rearrangement in the inter-granular relations with out loss of hardening that accompanies the higher temp process of annealing. – Work hardening. – Cold working. – Annealing. – Recovery. – Recrystalization. – Grain growth. www.indiandentalacademy.com
  • • Stainless steel archwires manufactured by A. J. WILCOCK SCIENTIFIC & ENGINEERING.LTD of Victoria, Australia, founded in 1946 by Late Arthur J. Wilcock, who had previously been employed at the Melbourne University Metallurgy School • The A J Wilcock archwire has been the backbone of Begg treatment ever since Dr BEGG started his technique. • The manufactures are continuously trying to improve the mechanical properties of these wires. • High tensile wires are available today. • Till recently, no other wire was found to be capable of duplicating their properties. www.indiandentalacademy.com
  • Properties of A J WILCOCK wires. • Round Austenitic S/S wire which is heat treated and cold drawn to its proper diameter from round wires of larger dimension. • High tensile strength. • Greater stiffness (load – deflection rate) than same size wire made of other materials like NiTi and TMA. • High resiliency. www.indiandentalacademy.com
  • • Toughness. • 0.008”-0.022” • Coiled and straight. • Regular grade to supreme grade (color coded) www.indiandentalacademy.com
  • REGULAR REGULAR PLUS SPECIAL PLUS SPECIAL PREMIUM SUPREME PREMIUM PLUS RESILIENCE YEILD STRENGTH www.indiandentalacademy.com
  • Regular grade • Lowest grade • Easier to bend • Used for practice bending and auxiliaries. • Can be used when archform distortion is not a problem or bite opening is not required. www.indiandentalacademy.com
  • Regular plus • Relatively easy to form. • More resilient than regular. • Used for making auxiliaries. • Used for making an archform when more pressure and resistance to deformation are desired. www.indiandentalacademy.com
  • Special grade • Highly resilient • Can be formed to intricate shapes with little danger of breaking. • Used as starting arches mostly www.indiandentalacademy.com
  • Special plus • Hardness and resiliency of 0.016” size is excellent for maintaining anchorage and for reducing overbites. • Chances of fracture is more. • Should be bent with caution. www.indiandentalacademy.com
  • Extra special plus • Unequalled in resiliency and hardness. • More difficult to bend. • More prone to fracture. www.indiandentalacademy.com
  • 0.009 0.008 0.010 0.011 0.012 0.014 0.016 0.018 0.020 PREMIUM PREMIUM PLUS SUPREME www.indiandentalacademy.com
  • PROCESS OF MANUFACTURING SPINNER STRAIGHTENING PULSE STRAIGHTENING www.indiandentalacademy.com
  • Mechanical process of straightening resistant materials usually in the cold drawn condition. the wire is pulled through high speed, rotating bronze rollers that torsionally twist into straight condition. The resultant deformation and decreased yield stress value makes it strain softened. SPINNER STRAIGHTENING www.indiandentalacademy.com
  • • The wire is pulsed in special machines the permit high tensile wires to be straightened. • The advantages –It permits highest tensile wire to be straightened. –Tensile yield stress is not altered. –Smoother surface of wire hence less friction. PULSE STRAIGHTENING www.indiandentalacademy.com
  • –Greater flexibility of springs fabricated. –Greater resiliency –Permits the usage of smaller diameter wire resulting in a light continuous force with minimal relaxation. www.indiandentalacademy.com
  • PULSE STRAIGHTENED TENSILE STRENGTH 8-12% LOAD DEFLECTION RATE 10% FOR 0.016” 235% FOR 0.020” FRICTIONAL RESISTANCE 50% INITIAL YEILD STRENGTH 33% COST www.indiandentalacademy.com
  • • Pulse Straightened wires have a smooth low friction surface with the same resilient properties as the coiled product, giving the added benefit of saving time to straighten the arch, posterior segments and hence, provide ease of use. Available in » Special Plus » Premium » Premium Plus » Supreme. www.indiandentalacademy.com
  • • The increase in the yield strength of the Australian wire is achieved by – Careful selection of materials with appropriate composition and properties – Cold working. 80 120 200 STAINLESS STEEL SUPREME WIRE STRESS STRAINwww.indiandentalacademy.com
  • High yield strength influences • Working range • Resiliency • Zero-stress relaxation • Formability www.indiandentalacademy.com
  • • Working range (max flexibility, spring back, elastic strain) Working range= Yield strength Modulus of elasticity Higher grade wire can be deflected over a greater distance without permanent deformation. They have better spring back than lower grade wires. Working range www.indiandentalacademy.com
  • Resiliency • MODULUS OF ELASTICITY  1/2 YIELD STRENGTH2. ELASTIC MODULUS • Same material with same modulus of elasticity and higher yield strength results in higher resiliency. • High grade wires absorbs or store more energy per unit area before it get deformed. • Higher resilient wire can work more to move the teeth. www.indiandentalacademy.com
  • Zero-stress relaxation • This is a form of slip by dislocation movement takes place at atomic level, which is resisted by high yield strength. • Ability of the wire to deliver constant force when subjected to external load, over a long period. • Newer wires maintain their configuration over a long periods against deforming forces and forces generated by the wires also remain practically unaffected over a long period www.indiandentalacademy.com
  • Formability F o r c e Deflection Failure point RESILIENCE FORMABILITY www.indiandentalacademy.com
  • • For the same material, greater the resiliency, greater the formability. • GREATER RESILIENT wires are more brittle than low grade wires. • So special care should be taken while bending these wires www.indiandentalacademy.com
  • • The properties of A J Wilcock wires are affected by the way, how it is straightened. • If the wires are straightened by reverse straining, the yield point of the wires reduces. (the way we straighten the wire manually) • In conventional manufacturing wire is straightened using rollers and spinners. This process is called as work softening due to reverse straining or Bauschinger effect. www.indiandentalacademy.com
  • Working range V/s resiliency TMA SMALLER DIAMETER SUPREME WIRE TMA SUPREME S T R E S S STRAIN MORE RESILIENT LESS ABILITY TO CORRECT ROTATIONS NiTi wires have a greater range than supreme and TMA wire But formability is poor Supreme wires are more ecconomical than TMA and NiTi wires. www.indiandentalacademy.com
  • Clinical tips and facts • The higher grade wires especially pulse straightened are excellent for applying constant force for a longer time without undergoing softening. • For a careless patient and patients with occlusal interference, chance of wire fracture is more. So low grade wire is preferred. • The wire used for making arches is selected according to the load deflection, we required. www.indiandentalacademy.com
  • HIGH LOAD DEFLECTION REQUIRED LOW LOAD DEFLECTION REQUIRED IN STAGE 1 0.016” / 0.018 PREMIUM OR PREMIUM PLUS THIRD STAGE TO MAINTAIN ARCH FORM 0.018” P AND P+ OR 0.020P TO AVOID UNDESERIABLE EFFECT OF TORQUING AUXILLARY 0.020” P IS INDICATED For smaller forces for alignment 0.014” PREMIUM 0.014” SPECIAL PLUS OR Sectionals of 0.012” PREMIUM PLUS OR smaller supreme wire according to malalignment during root torque and uprighting 0.012” P+ OR SMALLER SUPREME To attain high resiliency and spring back www.indiandentalacademy.com
  • Wires used in different stages of begg treatment 0.016”-Space present / space to be created. Average to deep bite cases-0.018 P+/P because it provides intrusive force on upper anteriors, resist lingual rolling of lower molars. Anterior open bite cases upper arch- 0.014P/P+ lower arch- 0.016P/P+ STAGE 1 www.indiandentalacademy.com
  • Rotational control MINIMUM MODERATE SEVERE 0.016” ss with V bends or offset bends 0.014” ss with V bend produces lesser forces Next visit- 0.016 ss 0.016/0.014” Niti with 0.014 SS base wire which is not engaged to malpositioned tooth. After correction NiTi is ommitedwww.indiandentalacademy.com
  • • A J Wilcock wires, due to its greater stiffness is beneficial for the objectives like bite opening and maintenance of archform,it is undesirable for the objective of alignment of crowded teeth. • This necessities the use of multi- looped arch form or sectional small diameter SS wire during alignment. • Another way is to use NiTi or TMA wire in conjunction with Australian wires. www.indiandentalacademy.com
  • STAGE II 0.018 P/P+ 0.020 P If stage 1 corrections involved extreme deep bite Distorted arch forms, Severe rotations They resist distobuccal rotational tendency of molars on the effect of class 1 elastics The degree of anchor bend should be reduced when using 0.020” than when using 0.018”www.indiandentalacademy.com
  • Usually completed within 1 month. 0.016” If discrepancy between premolar and molar positions are excessive it may require 2 months to reach 0.020” wire. PRESTAGE III www.indiandentalacademy.com
  • Base wire used is of 0.020 premium grade Three times stiffer than 0.020” special plus which used earlier (conventional). This will resist the vertical and horizontal reactions of auxiliaries and springs. STAGE III www.indiandentalacademy.com
  • MAA • Manufactured by Mollenhauer’s request-1984 • REQUIREMENTS • Light root moving force • Resist deformation • Base arch wire should resist vertical & transverse reactions of MAA- 0.018 premium plus 0.009 supreme www.indiandentalacademy.com
  •  Jenner auxiliary -0.012 supreme  Lingual root torquing auxiliary –0.012 P+ (refined begg) –0.014/0.016 special plus – conventional begg  Spec auxiliary – 0.009/0.010P+ –In stage III, if needed- 0.012P+ Reverse torquing auxiliary 0.012P+ on a 0.018/0.020 base wire  Uprighting spring 0.014P+ 0.019 supreme- Mollenhauers Mini uprighting spring www.indiandentalacademy.com
  • BENDING OF WIRE • Warm the wire by pulling through the fingers, because this wire have a brittle transition period slightly above the room temperature. • Wilcock pointed out that this wire is more likely to break when using round beak of the pliers. www.indiandentalacademy.com
  • FRACTURE More strain on the crystalline structures of the wire The point of stress on the wire are directly opposite to each other Greater force on one particular area TOO MUCH PRESSURE Damage to crystalline structures Fracture of wire Round beak of pliers When using a square beak, it produces an moment arm between the thumb and beak, reducing stress. www.indiandentalacademy.com
  • Crack propagation theory “There exist an relation between applied stress and internal stress at the head of dislocation pile ups seen in high and sharp yield point materials” POINT DEFECT AT HEAD OF DISLOCATION HEAD MINUTE CRACK TRANS GRANULAR CRACK PROPAGATION HIGH STRESS CONCFORCE www.indiandentalacademy.com
  • CARBIDE PRECIPITAES GRAINS ARE SPLITTED AND ENERGY IS RELEASED CRACK CONTINUES BLUNTING OF CRACK HEAD BY PLASTIC DEFORMATION CRACK PROPAGATION STOPS www.indiandentalacademy.com
  • AJO 1984 Nov Force relaxation in orthodontic arch wires - Hazel, et al Measurements of the force relaxation have been made in stainless steel, Elgiloy, and nitinol wires at 21° C and 37° C. All the wires were found to relax at 21° except NiTi. The rates of relaxation were found to vary widely; stainless steel wires produced by A J Wilcock relaxed significantly less than Elgiloy wires. www.indiandentalacademy.com
  • AJO 1984 Nov Force relaxation in orthodontic arch wires - Hazel, et al 0.016 round wires www.indiandentalacademy.com
  • The Wilcock wires were found to relax less than the other round wires tested, www.indiandentalacademy.com
  • A J WILCOCK Alpha Titanium wires Ti - 90% Al- 6% Va-4% • Ni – 0% so can be used in Ni sensitive patient • These wires have a molecular structure that resembles closely packed hexagonal lattice (TMA- BCC lattice). so easy deformation is not possible. • Absorbs Hydrogen and forms Titanium Hydride. With passage of time alloy becomes stiffer. www.indiandentalacademy.com
  • For over fifty years, "Australian Wire" has been a household name in orthodontics. The extra ordinary properties of these wires are due to the research and fine engineering skills employed in the processing of the wires. Wilcock wires are well known for their resilience and ability to withstand masticatory forces as well as being able to maintain their shape even when auxiliaries and elastics are used. There is no other wire which opens the bite as effectively as Wilcock wire. www.indiandentalacademy.com
  • THANK YOU DEVAKI MAM www.indiandentalacademy.com
  • For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com